Free Astronomy Magazine November-December 2023 ARABIC VERSION

the research team is to find its pos- sible origin, because none of the current theoretical models of planet formation predict that there could be a planet with these characteris- tics. Two possible scenarios for its formation have been proposed: in one of them it could have been pro- duced by collisions between massive protoplanets, that is between plan- ets which were in formation in that planetary system. These collisions might have elimi- nated the major part of the atmos- phere of TOI-1853b, leaving its solid nucleus exposed, which would ex- plain its high density within a mod- erate size. Another possibility is that TOI- 1853b might originally have been a gas giant similar to Jupiter, or even more massive, and could have taken a highly elliptical orbit due to inter- actions with other planets. This would have made it pass very close to its star, causing it to lose the outer layers of its atmosphere, and stabilizing its orbit at its current dis- tance from the star. “At the time being, we cannot dis- tinguish which of these formation scenarios is more plausible, al- though we should not rule out that later theoretical studies based on this discovery might lead to new models for the formation of very massive Neptunes” , explains Enric Pallé, a researcher at the IAC who participated in the study. TOI-1853b was first identified in 2020 as a planetary candidate with data from NASA’s TESS (Transiting Exoplanet Survey Satellite) which used the method of transits, which means observing the periodic dips in the light from a star caused by a planet in orbit round it when it crosses between us and the star. The confirmation that TOI-1853b is a planet, and the measurement of its mass and density were possible thanks to spectroscopic observa- tions of the star’s radial velocity ob- tained by the team using the HARPS-N (High Accuracy Radial Ve- locity Planet Searcher for the North- ern hemisphere) on the Telescopio Nazionale Galileo (TNG), at the Roque de los Muchachos Observa- tory, (La Palma, Canary Islands).  NOVEMBER-DECEMBER 2023 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 47 ﻟﻜﻦ اﻟﺠﺎﻧﺐ اﻷﻛﺜﺮ ﺗﺤﺪﻳ ﺎً ﻟﻔﺮﻳﻖ اﻟﺒﺤﺚ ﻫ ﻮ اﻟﻌﺜﻮر ﻋﲆ أﺻﻠﻪ ا ﺤﺘﻤﻞ ﻷﻧﻪ ﻟـﻢ ﻳﺘﻨﺒـﺄ أي ﻣـﻦ اﻟﻨﻤـﺎذج اﻟﻨﻈﺮﻳـﺔ اﻟﺤﺎﻟﻴــﺔ ﻟﺘﻜـﻮﻳﻦ اﻟﻜﻮﻛـﺐ ﺑﺈﻣﻜﺎﻧﻴـﺔ وﺟـﻮد ﻛﻮﻛـﺐ ﺑﻬــﺬه اﻟﺨﺼﺎﺋﺺ . ﺗﻢ اﻗﱰاح ﺳﻴﻨﺎرﻳﻮﻫ ﻣﺤﺘﻤﻠ ﻟﺘﻜﻮﻳﻨـﻪ : أﺣﺪﻫﻤﺎ ﻣﻦ ا ﻤﻜﻦ أن ﻳﻜﻮن ﻗﺪ ﻧـﺘﺞ ﻋـﻦ اﺻﻄﺪ اﻣﺎت ﺑ اﻟﻜﻮاﻛﺐ اﻷوﻟﻴﺔ اﻟﻀـﺨﻤﺔ أي ﺑ اﻟﻜﻮاﻛﺐ اﻟﺘﻲ ﻛﺎﻧﺖ ﰲ ﺣﺎﻟﺔ ﺗﻜـﻮﻳﻦ ﰲ ذﻟﻚ اﻟﻨﻈﺎم اﻟﻜﻮﻛﺒﻲ رﺑﻤـﺎ ﺗﻜـﻮن ﻫـﺬه اﻻﺻﻄﺪاﻣﺎت ﻗﺪ ﻗﻀﺖ ﻋﲆ اﻟﺠﺰء اﻷﻛﱪ ﻣﻦ اﻟﻐﻼف اﻟﺠﻮي ﻟﻠﻜﻮﻛﺐ TOI-1853b ﺗﺎرﻛﺔ ﻧﻮاﺗﻪ اﻟﺼﻠﺒﺔ ﻣﻜﺸﻮﻓﺔ وﻫـﻮ ﻣـﺎ ﻳﻔـ ﴪـ ﻛﺜﺎﻓﺘﻪ اﻟﻌﺎﻟﻴﺔ ﺿﻤﻦ ﺣﺠﻢ ﻣﻌﺘﺪل . ﻳﺘﺤﺪث اﻻﺣﺘﻤﺎل اﻵﺧﺮ ﺄنﺑ اﻟﻜﻮﻛـﺐ TOI- 1853b رﺑﻤﺎ ﻛﺎن ﰲ اﻷﺻﻞ ﻋﻤﻼﻗًـﺎ ﻏﺎزﻳـ ﺎً ﺎً ﺎﺑﻬ ﻣﺸ ﻟﻜﻮﻛـﺐ ا ﺸـﱰي أو ﺣﺘـﻰ أﻛﺜـﺮ ـــــ ـﺎﺟﺮ ﺗﻢ ﺗﺼﻮﻳﺮ ﻮﻛـﺐﻧ ﺘـﻮن ﺑﻮاﺳـﻄﺔ ﻓﻮ 2 ﻓـــــــــــــــﻲ 31 أﻏﺴـــــــــــــــﻄﺲ 1989 . ﺎﺳـــــــــــــــﺘﺨﺪام ﻣﺮﺷﺤﺎتﺿﻮﺋ ﺔ ﺑﺮ ﻘﺎﻟ ﺔ وﺧﻀﺮاء وزرﻗﺎء . ﺿﺨﺎﻣﺔ ورﺑﻤﺎ اﺗﺨﺬ ﻣﺪار اً إﻫﻠﻴﻠﺠﻴ ﺎً ﻟﻠﻐﺎﻳـﺔ ﺑﺴﺒﺐ اﻟﺘﻔـﺎﻋﻼت ﻣـﻊ اﻟﻜﻮاﻛـﺐ اﻷﺧـﺮى وﻫﺬا ﻣﻦ ﺷﺄﻧﻪ أ ن ﻳﺠﻌﻠﻪ ﻳﻤﺮ ﻗﺮﻳﺒﺎً ﺟﺪاً ﻣﻦ ﻧﺠﻤﻪ ﻣﺎ ﻳﻔ ﻘﺪه ﻃﺒﻘـﺎت اﻟﻐـﻼف اﻟﺠـﻮي اﻟﺨﺎرﺟﻴﺔ وﻳﺜﺒﺖ ﻣﺪاره ﻋﲆ ﺑﻌﺪه اﻟ ﺤﺎﱄ ﻋﻦ ﻧﺠﻤﻪ اﻷم . ﰲ اﻟﻮﻗﺖ اﻟﺤ ﺎﴐ ﻻ ﻳﻤﻜﻨﻨﺎ اﻟﺘﻤﻴﻴﺰ ﺑـ أي ﻣﻦ ﺳﻴﻨﺎرﻳﻮ ﻫﺎت اﻟﺘﻜﻮﻳﻦ ﻫﺬه ﻫﻮ اﻷﻛﺜـﺮ ﻗﺒـﻮﻻ ﻋـﲆ اﻟـﺮﻏﻢ ﻣـﻦ أﻧﻨـﺎ ﻻ ﻳﻨﺒﻐـﻲ أن ﻧﺴـﺘﺒﻌﺪ أن اﻟﺪراﺳـﺎت اﻟﻨﻈﺮﻳـﺔ اﻟﻼﺣﻘـﺔ ا ﺴﺘﻨﺪة إﱃ ﻫـﺬا اﻻﻛﺘﺸـﺎف ﻗـﺪ ﺗـﺆدي إﱃ ﻧﻤﺎ ذج ﺟﺪﻳﺪة ﻟﺘﺸﻜﻴﻞ ﻧﺒﺘﻮن ﺿﺨﻤﺔ ﺟﺪا " ﻳﴩح إﻧﺮﻳﻚ ﺑﺎﱄ. اﻟﺒﺎﺣﺚ ﰲ ﻣﻌﻬﺪ اﻟﻔﻴﺰﻳﺎء اﻟﻔﻠﻜﻴ ﺔ ﰲ ﺟﺰر اﻟﻜﻨـﺎري و اﻟـﺬي ﺷـﺎرك ﰲ اﻟﺪراﺳ .ﺔ ﺗﻢ ﺗﺤﺪﻳﺪ TOI-1853b ﻷول ﻣـﺮة ﰲ ﻋـﺎم 2020 ﻜﻮﻛﺐ ﻛ ﻣﺮﺷﺢ ﺑﺎﺳﺘﺨﺪام ﺑﻴﺎﻧﺎت ﻣﻦ ﺗﻴﺴﺲ ) اﻟﻘﻤﺮ اﻟﺼﻨﺎﻋ ﻲ ﺴﺢ اﻟﻜﻮاﻛﺐ اﻟﻨﺠﻤﻴﺔ اﻟﻌﺎﺑﺮة ( اﻟﺘﺎﺑﻊ ﻟ ﻮﻛﺎﻟﺔ ﻧﺎﺳﺎ واﻟﺬي اﺳﺘﺨﺪم ﻃﺮﻳﻘﺔ اﻟﻌﺒﻮر . إن ﻫﺬا ﻳﻌﻨـﻲ ﺑـﺄن ﻣﺮاﻗﺒـﺔ اﻻﻧﺨﻔﺎﺿـﺎت اﻟﺪورﻳﺔ ﰲ اﻟﻀﻮء اﻟﺼﺎدر ﻋﻦ ﻧﺠﻢ ﺑﺴـﺒﺐ وﺟﻮد ﻛﻮﻛﺐ ﰲ ﻣﺪار ﺣﻮﻟـﻪ . ﻋﻨـﺪﻣﺎ ﻳﻌـﱪ ﺑﻴﻨﻨﺎ وﺑ اﻟﻨﺠﻢ . ﻟﻘﺪ ﺗﻢ اﻟﺘﺄﻛﻴـﺪ ن ﺑـﺄ TOI-1853b ﻛﻮﻛـﺐ ﺑﺎﻟﻔﻌﻞ وﺗﻢ ﻛﺬﻟﻚ ﻗﻴـﺎس ﻛﺘﻠﺘـﻪ وﻛﺜﺎﻓﺘـﻪ ﺑﻔﻀﻞ اﻷرﺻﺎد اﻟﻄﻴﻔﻴﺔ ﻟﻠﴪﻋﺔ اﻟﺸﻌﺎﻋﻴﺔ ﻟﻠﻨﺠﻢ واﻟﺘﻲ ﺣﺼﻞ ﻋﻠﻴﻬﺎ اﻟﻔﺮﻳﻖ ﺑﺎﺳﺘﺨﺪام ( إن - ﻫﺎرﺑﺲ ) ﻣﻄﻴﺎف ﺑﺎﺣﺚ اﻟﻜ ﻮاﻛﺐ ﻋﺎﱄ اﻟﺪﻗﺔ واﻟﴪﻋﺔ اﻟﺸﻌﺎﻋﻴ ﻪ ﻟﻠﻨﺼﻒ اﻟﺸـﻤﺎﱄ ﻣﻦ اﻟﻜﺮة اﻷرﺿﻴﺔ ( وا ﺜﺒﺖ ﻋـﲆ ﺗﻠﺴـﻜﻮب ﻏﺎﻟﻴﻠﻴﻮ اﻟﻮﻃﻨﻲ ا ﻮﺟﻮد ﰲ ﻣﺮﺻـﺪ روﻛـﻲ دي ﻟﻮس ﻣﻮﺗﺸﺎﺗﺸﻮس ﺟﺰﻳﺮة ﰲ ﻻ ﺑﺎ ـﺎ، اﻟﺘﺎﺑﻌﺔ ﻟ ﺠﺰر اﻟﻜﻨﺎري .( ﻧﻮﻓﻤﺒﺮ - ﺩﻳﺴﻤﺒﺮ 2 0 2 3